Manufacturing process of liquid crystal display device, and liquid crystal display device

ABSTRACT

A manufacturing process of an LCD device of the invention includes forming a first substrate provided with a pixel part with thin film transistors and a seal portion arranged around the pixel part, forming a second substrate opposed to the first substrate, filling a liquid crystal layer between the first substrate and the second substrate, and adhering the first substrate to the second substrate with a sealant provided for the seal portion, wherein the forming the first substrate includes forming a semiconductor layer composing the thin film transistor, forming in the seal portion a semiconductor connection layer made of a same material as the semiconductor layer, and forming an organic interlayer insulating film, wherein the forming the semiconductor layer and the forming the semiconductor connection layer are performed in the same step.

INCORPORATION BY REFERENCE

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2008-077894, filed on Mar. 25 2008, thedisclosure of which is incorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a manufacturing process of a liquidcrystal display (LCD) device and an LCD device, and particularly relatesto a manufacturing process including a step for sealing a liquid crystallayer with a sealant and a structure of a seal portion thereof.

2. Background Art

In recent years, an LCD device is widely used as a high-resolutiondisplay device. This LCD device includes two substrates. The one hasswitching elements such as thin film transistors (TFTs) (hereinafter,referred to as a TFT substrate) and the other has a color filter and ablack matrix (hereinafter, referred to as a color filter substrate). Inthis LCD device, a liquid crystal material is sandwiched between the TFTsubstrate and the color filter substrate. These substrates are adheredby using a sealant on a periphery thereof, and a liquid crystal layer issealed.

In a general LCD device, the sealant adheres to an inorganic protectiveinsulating film extending to the periphery of the TFT substrate. Inrecent years, in order to improve an aperture ratio of a TFT substrate,an LCD device is put to practical use in which an organic interlayerinsulating film is formed on an inorganic protective insulating filmHowever, an adhesive force between an organic interlayer insulating filmand a sealant decreases compared with one between an inorganicprotective insulating film and a sealant. Therefore the sealant isdesigned to be arranged on the inorganic protective insulating film byadding a process of removing the organic interlayer insulating film onthe seal portion of the TFT substrate. In this way, an improvement ofadhesiveness is achieved.

An example of an LCD device having an organic interlayer insulating filmis disclosed in Japanese Patent Application Laid-Open No. 2003-167258.The LCD device described in this gazette is shown in FIG. 11. FIG. 11Ais a cross sectional view of an outer peripheral part thereof, and FIG.11B is a cross sectional view of a pixel part. As shown in FIG. 11B, theTFT structure of this LCD device is a structure called a top gate typeor a planar type. In the top gate type (the planer type) TFT structure,a polysilicon semiconductor layer 32, a gate insulating film 33, and agate wiring 34 are formed in this order on a glass substrate 31. Aninorganic protective insulating film 35 and an organic interlayerinsulating film 36 are formed in this order on an upper surface of thegate wiring 34. Accordingly, by removing only two layers of the organicinterlayer insulating film 36 and the inorganic protective insulatingfilm 35 using an etching step, a contact hole can be formed. At thattime, in a seal portion in which a sealant 37 is formed, since the layerstructure is identical with that of the pixel part, the organicinterlayer insulating film 36 and the inorganic protective insulatingfilm 35 in the seal portion are also removed similarly. However, aninorganic interlayer insulating film 38 formed thereunder remainswithout being removed. Accordingly, the gate wiring 34 formed under theinorganic interlayer insulating film 38 can not be exposed in the sealportion during a contact hole formation process.

SUMMARY

An exemplary object of the present invention is to provide amanufacturing process of a high reliable LCD device having strongadhesive force between a TFT substrate and a sealant without additionalprocess, and this LCD device.

A manufacturing process of an LCD device according to an exemplaryaspect of the present invention includes forming a first substrateprovided with a pixel part with thin film transistors and a seal portionarranged around the pixel part, forming a second substrate opposed tothe first substrate, filling a liquid crystal layer between the firstsubstrate and the second substrate, and adhering the first substrate tothe second substrate with a sealant provided for the seal portion,wherein the forming the first substrate includes forming a semiconductorlayer composing the thin film transistor, forming in the seal portion asemiconductor connection layer made of a same material as thesemiconductor layer, and forming an organic interlayer insulating film,wherein the forming the semiconductor layer and the forming thesemiconductor connection layer are performed in the same step.

An LCD device according to another aspect of the present inventionincludes a first substrate provided with a pixel part with thin filmtransistors and a seal portion arranged around the pixel part, a secondsubstrate opposed to the first substrate, a liquid crystal layer filledbetween the first substrate and the second substrate, and a sealantprovided for the seal portion in which the first substrate is adhered tothe second substrate, wherein the first substrate includes an organicinterlayer insulating film at least, the seal portion includes asemiconductor connection layer made of a same material as asemiconductor layer composing the thin film transistor, and thesemiconductor connection layer is arranged in contact with the sealant.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary features and advantages of the present invention will becomeapparent from the following detailed description when taken with theaccompanying drawings in which:

FIG. 1 is a cross sectional view of an LCD device according to a firstexemplary embodiment of the present invention;

FIGS. 2A to 2C are cross sectional views illustrating a manufacturingprocess of a TFT substrate according to the first exemplary embodimentof the present invention;

FIGS. 3A to 3C are cross sectional views illustrating a manufacturingprocess of the TFT substrate according to the first exemplary embodimentof the present invention;

FIGS. 4A to 4C are cross sectional views illustrating a manufacturingprocess of the TFT substrate according to the first exemplary embodimentof the present invention;

FIGS. 5A to 5C are cross sectional views illustrating a manufacturingprocess of the TFT substrate according to the first exemplary embodimentof the present invention;

FIG. 6 is a cross sectional view illustrating a manufacturing process ofthe TFT substrate according to the first exemplary embodiment of thepresent invention;

FIGS. 7A and 7B are cross sectional views illustrating a manufacturingprocess of a TFT substrate according to a second exemplary embodiment ofthe present invention;

FIG. 8 is a cross sectional view of a TFT substrate according to a thirdexemplary embodiment of the present invention;

FIGS. 9A to 9C are cross sectional views illustrating a manufacturingprocess of a TFT substrate according to a fourth exemplary embodiment ofthe present

FIGS. 10A and 10B are cross sectional views illustrating a manufacturingprocess of the TFT substrate according to the fourth exemplaryembodiment of the present invention;

FIGS. 11A and 11B are cross sectional views of an LCD device of arelated art of the present invention; and

FIGS. 12A to 12D are cross sectional views illustrating a manufacturingprocess of a TFT substrate of a related art of the present invention.

EXEMPLARY EMBODIMENT

Exemplary embodiments of the present invention will now be described indetail in accordance with the accompanying drawings.

FIG. 1 is a cross sectional view of an LCD device according to a firstexemplary embodiment of the present invention. As shown in FIG. 1, in anLCD device 1, a liquid crystal layer 4 is sandwiched between a TFTsubstrate 2 and a color filter substrate 3. The TFT substrate 2 includesa pixel part 5, a G/D conversion part 6 for connecting a drain wiring toa gate wiring which is used as a drain lead wiring, a seal portion 7,and a terminal portion 8.

In the pixel part 5, a thin-film transistor (TFT) is formed whichincludes a channel region consisting of an amorphous silicon (a-Si) film9, a gate insulating film 10, a gate electrode 152, a source electrode11, and a drain electrode 142. And protective insulating film 12 andorganic interlayer insulating film 13 are formed all over the TFTsubstrate 2. In a contact region of the source electrode 11 and a drainwiring 14 connected to the drain electrode 142, the protectiveinsulating film 12 and the organic interlayer insulating film 13 areremoved. On the other hand, in a contact region of a common electrode 16located in the same layer as a gate wiring 15 connected to the gateelectrode 152, a gate insulating film 10 is also removed in addition tothe protective insulating film 12 and the organic interlayer insulatingfilm 13. That is, a contact hole is opened whose depth is different fromthat of the contact hole on the source electrode 11 and a drain wiring14.

In the seal portion 7, a semiconductor connection layer 17 consisting ofan amorphous silicon (a-Si) film is formed on the same layer as thechannel region in the TFT. The protective insulating film 12 and theorganic interlayer insulating film 13 on the semiconductor connectionlayer 17 are removed, and the semiconductor connection layer 17 formedon the gate insulating film 10 is exposed. The exposed semiconductorconnection layer 17 is contacted with a sealant 18.

In the G/D conversion part 6, in order that the drain wiring 14 formedon the same layer as the channel region in the TFT will not be exposedin the seal portion 7, the drain wiring 14 is joined to the gate wiring15.

A terminal portion 8 is a terminal for connecting the LCD device 1 to anexternal circuit, which is connected to the gate wiring 15.

On the other hand, the color filter substrate 3 opposed to the TFTsubstrate 2 includes a glass substrate 51, a black matrix (BM) 52 formedthereon, a color pixel 53, a flattening film 54 consisting of an organicmaterial, and an alignment film 55. In the LCD device according to thisexemplary embodiment, the TFT substrate 2 is adhered to the color filtersubstrate 3 by the sealant 18 arranged in the seal portion 7 locatednear the periphery of the TFT substrate 2. The liquid crystal layer 4 isfilled between the TFT substrate 2 and the color filter substrate 3.

The sealant 18 is generally made of epoxy resin or the like. Withrespect to adhesive strength, one between the amorphous silicon (a-Si)film as a semiconductor material and the sealant 18 is the strongest,one between a transparent conductive film and the sealant 18 is the nextstrongest, and one between the organic interlayer insulating film 13 andthe sealant 18 is the weakest. In this exemplary embodiment, since thesemiconductor connection layer 17 made of an amorphous silicon (a-Si)film is formed in the region adhering to the sealant 18, the adhesiveforce between the sealant 18 and the TFT substrate 2 can bestrengthened. Moreover, unlike an electrode layer made of a metallicmaterial, the semiconductor material is not corroded by contacting witha sealant. Therefore, a connection part with the sealant 18 does notdeteriorate with aging, and an LCD device with high reliability isobtained.

A manufacturing process of the TFT substrate 2 according to the firstexemplary embodiment is described referring to FIGS. 2 to C.

First, as shown in FIG. 2A, a metal layer for the gate wiring 15 isformed on a glass substrate 21. As examples of metal, a pure metal, suchas Cr, Al, Mo, Ti and Cu, or an alloy including these metals can beused. A laminated structure consisting of two or more kinds of suchmetal may be used. A metal evaporation process can be used for a filmdeposition process, more preferably a sputtering technique is used.

A resist layer 22 is formed into a prescribed pattern by means of aphotolithography process (FIG. 2A). A pattern of the gate wiring 15 isformed by etching the metal layer using this resist layer 22 as a mask(FIG. 2B). Then the resist layer 22 is removed (FIG. 2C).

Next, as shown in FIG. 3A, the gate insulating film 10 is formed on thegate wiring 15. A transparent insulating film made of an inorganicmaterial, such as a SiO₂ film and a SiN_(x) film, can be used for thegate insulating film 10. A CVD (Chemical Vapor Deposition) process canbe used for deposition thereof. Next, the amorphous silicon (a-Si) film9 as a channel region and the n⁺a-Si film 23 as a drain or sourcecontact region are continuously formed on the gate insulating film 10.These films are formed by means of CVD process or the like. After thedeposition, a prescribed pattern is formed by etching the films with apatterned resist film 22 using a photolithography process (FIG. 3A, B,C). At the same time, the semiconductor connection layer 17 is formed onthe seal portion 7 by using an amorphous silicon (a-Si) film forming achannel region of the TFT (FIG. 3C).

Next, a metallic film as the drain wiring 14 or the source wiring 24 isformed (FIG. 4A). As examples of a metallic film, a pure metal, such asCr, Al, Mo, Ti and Cu, or an alloy including these metals can be used. Alaminated structure consisting of two or more kinds of such metal may beused. A sputtering technique can be preferably used in the process ofthe metallic film deposition as well as the gate wiring formation. A TFTpattern is formed by using a resist film 22 as a mask by means of aphotolithography process. A drain region and a source region areseparated by a channel etching process (FIG. 4B). As a result, aninverted-staggered type TFT structure is completed (FIG. 4C). It ispreferable to perform the channel etching by means of a dry etchingprocess. Although FIG. 4 shows the manufacturing process in which thechannel etching is performed before removing the resist film 22, it maybe also performed after removing the resist.

Next, as shown in FIG. 5, after forming the drain wiring 14 and thesource wiring 24, the protective insulating film 12 is formed thereon. Atransparent insulating film including an inorganic material or anorganic material can be used as the protective insulating film 12. Inthis exemplary embodiment, the inorganic protective insulating film 12made of a SiN_(x) film is formed by the CVD process. Next, the organicinterlayer insulating film 13 is formed. As an example of the organicinterlayer insulating film 13, an acrylic resin or the like can be used.Next, a resist film 222 on the seal portion 7 and the respective contactregions, which are located in the source electrode 11, the drain wiring14 connected to the drain electrode and the common electrode 16, isremoved by means of a photolithography process (FIG. 5A).

The organic interlayer insulating film 13 is etched by using this resistfilm 222 as a mask (FIG. 5B). For example, a dry etching with an oxygen(O₂) gas can be used for this etching. In order to make the etching rateof the organic interlayer insulating film 13 fast, it is more preferableto etch by using the gas added with a CF₄ (tetrafluoromethane) gas.Next, successively, the protective insulating films 12, which arelocated on the source electrode 11, the drain wiring 14, and the commonelectrode 16, and the gate insulating film 10 which is located on thecommon electrode 16 are removed by means of etching process (FIG. 5C).For example, the etching process is performed by means of a dry etchingwith a CF₄ gas or an SF₆ (sulfur hexafluoride) gas. The protectiveinsulating film 12 in the seal portion 7 is also removed by the etchingprocess at the same time. However, since the semiconductor connectionlayer 17 made of an amorphous silicon (a-Si) film is formed under theprotective insulating film 12 and functions as an etching stopper, thegate insulating film 10 thereunder is not removed during the etchingprocess (FIG. 5C). That is, in the case of the inverted-staggered typeTFT structure, unlike a top gate type (planer type) TFT structure, theamorphous silicon (a-Si) film 9 as the channel region in the TFT isformed on an upper layer of the gate wiring 15. Therefore, thesemiconductor connection layer 17 formed in the same layer as thechannel region can be used as an etching stopper. By using the aboveprocess, the formation of the contact holes which are located on thesource electrode 11, the drain wiring 14, and the common electrode 16,and the removal of the organic interlayer insulating film 13 in the sealportion 7 are performed by the same process. The contact holes mayinclude a second contact hole formed on the drain wiring and the sourcewiring. A fourth contact hole may be formed on the drain wiring and thesource wiring.

It is desirable that an area of the semiconductor connection layer 17formed in the seal portion 7 is larger than an area of an opening 25which is opened by etching the protective insulating film 12 and theorganic interlayer insulating film 13. The reason is as follows. Anetching in the horizontal direction progresses by dry etching as well asan etching in the depth direction progressing. For this reason, the areaof the opening 25 after etching is larger than the area of the opening25 which is formed by using the resist film as the mask in early stagesof etching. By forming the semiconductor connection layer 17 with thearea greater than that of the opening 25 formed by using the resistfilm, the gate insulating film 10 located under the semiconductorconnection layer 17 is not exposed even if side etching progressesduring etching the contact hole. Therefore, the gate insulating film 10is protected by the semiconductor connection layer 17.

Next, as shown in FIG. 6, after forming the contact hole, a transparentconductive film 26 is formed. An indium tin oxide (ITO), an indium zincoxide (IZO), etc. can be used for the transparent conductive film 26. Asputtering process is preferably used for a deposition process. Thetransparent conductive film 26 is patterned by using a photomask afterdeposition, at the same time the transparent conductive film 26 formedin the seal portion 7 is removed Finally, the TFT substrate 2 iscompleted by forming an alignment film made of a polyimide film, forexample.

As mentioned above, according to the manufacturing process of thisexemplary embodiment, the semiconductor connection layer 17 functions asan etching stopper. Therefore, the organic interlayer insulating film 13in the seal portion 7 can be removed by the same process as that offorming the contact holes in the source electrode 11, the drain wiring14, and the common electrode 16, without adding a new process.

Next, a second exemplary embodiment of the present invention isdescribed. In the second exemplary embodiment, photosensitivity is givento the organic interlayer insulating film 13 used in the first exemplaryembodiment. FIG. 7 is a cross sectional view illustrating amanufacturing process of a TFT substrate 2 according to the secondexemplary embodiment of the present invention.

According to the second exemplary embodiment of the present invention,the TFT substrate 2 is formed by the same process as the first exemplaryembodiment up to the step for forming the protective insulating film 12.Next, in the process of opening a contact hole, a photosensitive organicinterlayer insulating film 13-1 is formed A spin coater or a rollcoater, etc. can be used in a coating process. Next, by means of aphotolithography process, the organic interlayer insulating film 13-1 isexposed and developed. As a result, the organic interlayer insulatingfilm 13-1, which is formed in the contact hole region and the area forthe sealant 18 in the seal portion 7, can be removed without using aresist coating process (FIG. 7A).

Next, the protective insulating film 12 and the gate insulating film 10are removed by etching with a mask of the organic interlayer insulatingfilm 13-1 (FIG. 7B). At this time, the protective insulating film 12 onthe area for the sealant 18 in the seal portion 7 is removed by thisetching process. However, since the semiconductor connection layer 17made of an amorphous silicon (a-Si) film, which is arranged in the lowerlayer of the protective insulating film 12 as well as the firstexemplary embodiment, functions as an etching stopper, the gateinsulating film 10 arranged in the further lower layer is not removed bythis etching process. Therefore, according to this exemplary embodiment,the structure, which includes the contact hole region where the gateinsulating film 10 is removed and the seal portion 7 covered with thesemiconductor connection layer 17 and the gate insulating film 10, canbe formed by the process which skips one step for resist film formingprocess compared with that of the first exemplary embodiment.

Next, a third exemplary embodiment of the present invention isdescribed. In the third exemplary embodiment, an organic interlayerinsulating film 13-2 is formed instead of the protective insulating film12 and the organic interlayer insulating film 13 in the first exemplaryembodiment. FIG. 8 is a cross sectional view of a TFT substrate 2according to the third exemplary embodiment of the present invention.The TFT substrate 2 in this exemplary embodiment is manufactured by thesame process as that of the first exemplary embodiment until the step offorming the metallic film which is used as the drain wiring 14 and thesource wiring 24. Next, the organic interlayer insulating film 13-2 isformed by a coating process. And in order to open contact holes, theorganic interlayer insulating film 13-2 is removed on the region of thesource electrode 11, the drain wiring 14, the common electrode 16, andthe area for the sealant 18 in the seal portion 7. This process iscarried out by means of the conventional photolithography process andetching process by using a resist film as a mask. If the photosensitiveorganic protective insulating film 13-2 is used, these contact holes canbe formed by a photolithography process only. Next, the gate insulatingfilm 10 is removed by means of the dry etching process etc. As a result,by only one step of a photolithography process and an etching process,the opening of the contact holes for the source electrode 11, the drainwiring 14, and the common electrode 16 and the removal of the organicinterlayer insulating film 13-2 on the area for the sealant 18 in theseal portion 7 can be carried out. Since the step for forming aprotective insulating film 12 made of an inorganic material can bedeleted by the above process, an LCD device can be manufactured at muchreduced cost.

Next, a fourth exemplary embodiment of the present invention isdescribed. In the fourth exemplary embodiment, the organic interlayerinsulating film 13 is removed not only in the seal portion 7 but in theterminal portion 8. FIGS. 9 and 10 are cross sectional viewsillustrating a manufacturing process of a TFT substrate 2 according tothe fourth exemplary embodiment of the present invention.

As shown in FIG. 9A, an amorphous silicon (a-Si) film 9 as a channelregion and an n⁺a-Si film 23 as a contact region of a drain and a sourcein the TFT are formed by means of the same process as that of the firstexemplary embodiment. At this time, the semiconductor connection layer17 made of an amorphous silicon (a-Si) film is formed not only in theseal portion 7 but in the terminal portion 8 in this exemplaryembodiment. It is desirable that a part of the semiconductor connectionlayer 17 which extends to the display area (pixel) side from the sealportion 7 is arranged in the region where the organic interlayerinsulating film 13 and the protective insulating film 12 are partiallyoverlapped after etched. It is because an influence of a side etchingcan be prevented which arises in the etching step of the organicinterlayer insulating film 13 as mentioned later.

Next, the resist film 22 is formed into a prescribed pattern by means ofa photolithography process, and the pattern for TFT is formed by anetching step. Next, up to the step for coating the organic interlayerinsulating film 13, the same steps as those of the first exemplaryembodiment are carried out. Next, in order to form contact holes, aresist pattern is formed on the organic interlayer insulating film 13 bymeans of a photolithography process (FIG. 9A). By using the resist film22 as a mask, the organic interlayer insulating film 13 is removed alongthe pattern thereof (FIG. 9B). Next, the protective insulating film 12and the gate insulating film 10 are removed, then contact holes areformed (FIG. 9C). At that time, the semiconductor connection layer 17made of an amorphous silicon (a-Si) film arranged in terminal portion 8and the seal portion 7 is not removed, and functions as an etchingstopper for the gate insulating film 10. Therefore, the formation of thecontact hole and the removal of the protective insulating film 12 andthe organic interlayer insulating film 13 in the seal portion 7 and theterminal portion 8 can be carried out in the same process step.

As mentioned above, the part of the semiconductor connection layer 17which extends to the display area (pixel) side from the seal portion 7is arranged in the region where the organic interlayer insulating film13 and the protective insulating film 12 are partially overlapped.Therefore, even if the side of the protective insulating film 12 and theorganic interlayer insulating film 13 recede by the side etching, thegate insulating film 10 arranged under the overlapped region can not beetched.

Next, the semiconductor connection layer 17 in the terminal portion 8and the seal portion 7 is removed by using the same resist mask (FIG.10A). The reason is as follows. If an amorphous silicon (a-Si) film isused as the semiconductor connection layer 17, terminals areshort-circuited because amorphous silicon (a-Si) film is electricallyconductive. In order to avoid such short cut, the semiconductorconnection layer 17 in the terminal portion 8 is removed. Finally, atransparent conductive film 26 is formed by the same process as that ofthe first exemplary embodiment, and then the TFT substrate 2 accordingto this exemplary embodiment is completed (FIG. 10B).

By using this process, the organic interlayer insulating film 13 can beremoved not only in the seal portion 7 but in the terminal portion 8without adding another photolithography process. Therefore therepair-ability of the terminal portion 8 can be improved. The reason isas follows. An ACF (anisotropic conducting film) connection is generallyused for connection between terminals of an LCD device and an externalcircuit board. In this case, if the organic insulating film remained inthe terminal portion, the level difference increases. Therefore therepair-ability deteriorates. However, since the organic insulating filmin the terminal portion 8 is also removed according to this exemplaryembodiment, the repair-ability of the terminal portion 8 can beimproved.

In the seal portion 7 of the TFT substrate 2 according to this exemplaryembodiment, the organic interlayer insulating film 13, the protectiveinsulating film 12 made of inorganic material, and the semiconductorconnection layer 17 are removed. However, because the sealant 18 adheresto the gate insulating film 10 made of inorganic material, strongadhesive strength thereof can be obtained.

In this exemplary embodiment, the organic interlayer insulating film 13may have photosensitivity as well as in the second exemplary embodiment,and the organic interlayer insulating film 13-1 may be patterned by aphotolithography process. The organic interlayer insulating film 13-2consisting of one layer may be used instead of using both the protectiveinsulating film 12 and the organic interlayer insulating film 13 as wellas in the third exemplary embodiment.

Next, a manufacturing process of a related LCD device having an organicinterlayer insulating film is described referring to FIG. 12. Therelated LCD device is provided with an inverted-staggered type TFT.First, a photosensitive organic interlayer insulating film 36-1 iscoated on the whole surface of the protective insulating film 35 made ofan inorganic material. Then, a contact hole and an opening 39corresponding to a pattern of a seal portion 7 are formed in the organicinterlayer insulating film 36-1 by means of the first photolithographystep (FIG. 12A). Next, a resist film is coated on the whole surface ofthe organic interlayer insulating film 36-1 so that the opening 39 maybe buried. Next, a resist film 40 is patterned by means of the secondphotolithography step so that the opening 39 in a seal portion 7 may becovered (FIG. 12B). The protective insulating film 35 and a gateinsulating film 33 in a contact hole region are removed in a step foretching by using the resist film 40 as a mask (FIG. 12C). Finally, theresist film is stripped (FIG. 12D).

However, in the related LCD device mentioned above, as shown in FIG.12D, the organic interlayer insulating film 36-1, the protectiveinsulating film 35, and the gate insulating film 33 must be removed inorder to form the contact hole for the drain wiring 41 connected to thedrain electrode provided on the gate insulating film 33, and the contacthole for the common electrode 42 provided on the same layer as the gatewiring 34. If the organic interlayer insulating film 36-1 in the sealportion is removed by the same process, the protective insulating film35 and the gate insulating film 33 in the seal portion will be removedas well as the organic interlayer insulating film 36-1. As a result, thegate wiring 34 can be exposed in the seal portion.

Therefore, in the related LCD device, there is the problem that thewiring material which composes gate wiring 34 is corroded by contactingthe sealant. Since impurities penetrate the liquid crystal layer by thecorrosion, there are problems that display failure has arisen, and theadhesiveness between the sealant and the metallic wiring hasdeteriorated.

In order to avoid these problems, as described with FIG. 12, it isnecessary that the process for forming the contact hole and the processfor forming the seal portion with the gate insulating film 33 remainingare separately performed. Therefore, since it is necessary to performtwo times of photolithography processes there are the problems that thenumber of processes increases and a manufacturing cost rises.

An exemplary advantage according to the invention is that an increase inthe number of processes can be controlled because the step for formingthe contact hole in the TFT substrate and the step for opening theorganic interlayer insulating film in the seal portion can be performedat the same process. A high reliable LCD device having strong adhesiveforce between a TFT substrate and a sealant can be obtained.

While the invention has been particularly shown and described withreference to exemplary embodiments thereof the invention is not limitedto these embodiments. It will be understood by those of ordinary skillin the art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the present invention asdefined by the claims.

Further, it is the inventor's intention to retain all equivalents of theclaimed invention even if the claims are amended during prosecution.

What is claimed is:
 1. A manufacturing process of a liquid crystaldisplay device, comprising: forming a first substrate provided with apixel part with thin film transistors and a seal portion arranged aroundsaid pixel part; forming a second substrate opposed to said firstsubstrate; filling a liquid crystal layer between said first substrateand said second substrate; and adhering said first substrate to saidsecond substrate with a sealant provided for said seal portion, whereinsaid forming said first substrate comprises: forming a semiconductorlayer composing said thin film transistor, forming in said seal portiona semiconductor connection layer made of a same material as saidsemiconductor layer, and forming an organic interlayer insulating film;wherein said forming said semiconductor layer and said forming saidsemiconductor connection layer are performed in the same step, and saidfirst substrate comprises at least the organic interlayer insulatingfilm, said seal portion comprises the semiconductor connection layerwhich made of a same material as the semiconductor layer composing saidthin film transistor, and said sealant is placed on a bottom of anopening between a terminal portion and a Gate wiring/Drain wiringconversion portion from where said semiconductor connection layerreveals and is surrounded by a protective insulating film, the organicinterlayer insulating film and a transparent conductive film.
 2. Themanufacturing process of a liquid crystal display device according toclaim 1, wherein said seal portion comprises a gate wiring connected toa gate electrode of said thin film transistor, a gate insulating filmformed on said gate wiring, said semiconductor connection layer formedon said gate insulating film, and said organic interlayer insulatingfilm, wherein said forming said first substrate further comprisesremoving said gate insulating film in regions except said seal portion,and forming an opening where said semiconductor connection layer isexposed in a part of said organic interlayer insulating film in saidseal portion, wherein said semiconductor connection layer is used as anetching mask in removing said gate insulating film.
 3. The manufacturingprocess of a liquid crystal display device according to claim 1, whereinsaid first substrate comprises a gate wiring connected to a gateelectrode of said thin film transistor, a common electrode made of asame material as said gate wiring, a gate insulating film formed on saidgate wiring and said common electrode, said semiconductor layer formedon said gate insulating film, a drain wiring and a source wiring whichare connected to a drain electrode and a source electrode of said thinfilm transistor, respectively, and said organic interlayer insulatingfilm formed on said drain wiring and said source wiring, wherein saidforming said first substrate further comprises forming a first contacthole by removing a part of said gate insulating film and said organicinterlayer insulating film on said common electrode, forming a secondcontact hole by removing a part of said organic interlayer insulatingfilm on said drain wiring and said source wiring, and forming an openingwhere said semiconductor connection layer is exposed by removing saidorganic interlayer insulating film in said seal portion, wherein saidforming said first contact hole, said forming said second contact hole,and said forming said opening are performed in the same photolithographystep and etching step.
 4. The manufacturing process of a liquid crystaldisplay device according to claim 1, wherein said first substratecomprises a gate wiring connected to a gate electrode of said thin filmtransistor, a common electrode made of a same material as said gatewiring, a gate insulating film formed on said gate wiring and saidcommon electrode, said semiconductor layer formed on said gateinsulating film, a drain wiring and a source wiring which are connectedto a drain electrode and a source electrode of said thin filmtransistor, respectively, a protective insulating film formed on saiddrain wiring and said source wiring, and said organic interlayerinsulating film formed on said protective insulating film, wherein saidforming said first substrate further comprises forming a third contacthole by removing a part of said gate insulating film, said protectiveinsulating film, and said organic interlayer insulating film on saidcommon electrode, respectively, forming a fourth contact hole byremoving a part of said protective insulating film and said organicinterlayer insulating film on said drain wiring and said source wiring,and forming an opening where said semiconductor connection layer isexposed by removing said organic interlayer insulating film and saidprotective insulating film in said seal portion, wherein said formingsaid third contact hole, said forming said fourth contact hole, and saidforming said opening are performed in the same photolithography step andetching step.
 5. The manufacturing process of a liquid crystal displaydevice according to claim 2, wherein said forming said opening comprisesforming an etching mask on said organic interlayer insulating film,forming a mask pattern having a mask opening region removed a part ofsaid etching mask, and removing a part of said organic interlayerinsulating film by using said mask pattern, wherein a region, where saidmask opening region is projected on a surface of said semiconductorconnection layer, is surrounded by said semiconductor connection layer.6. The manufacturing process of a liquid crystal display deviceaccording to claim 1, wherein said forming said organic interlayerinsulating film comprises a photolithography step using a photosensitiveorganic interlayer insulating film material.
 7. The manufacturingprocess of a liquid crystal display device according to claim 1, whereinsaid first substrate comprises a terminal portion outside of said sealportion, said terminal portion is connected to said pixel part by a leadwiring crossing said seal portion, wherein said forming said firstsubstrate further comprises forming said semiconductor connection layerin said terminal portion, and said forming said semiconductor connectionlayer in said seal portion and said forming said semiconductorconnection layer in said terminal portion are performed in the samestep.
 8. A liquid crystal display device, comprising: a first substrateprovided with a pixel part with thin film transistors and a seal portionarranged around said pixel part on a same surface of said firstsubstrate; a second substrate opposed to said first substrate; a liquidcrystal layer filled between said first substrate and said secondsubstrate; and a sealant provided for said seal portion in which saidfirst substrate is adhered to said second substrate, wherein said firstsubstrate comprises at least an organic interlayer insulating film, saidseal portion comprises a semiconductor connection layer which is made ofa same material as a semiconductor layer composing said thin filmtransistor, and said sealant is placed on a bottom of an opening betweena terminal portion and a Gate wiring/Drain wiring conversion portionfrom where said semiconductor connection layer reveals and is surroundedby a protective insulating film, an organic interlayer insulating filmand a transparent conductive film.
 9. The liquid crystal display deviceaccording to claim 8, wherein said seal portion comprises the gatewiring connected to a gate electrode of said thin film transistor, agate insulating film formed on said gate wiring, said semiconductorconnection layer formed on said gate insulating film, said organicinterlayer insulating film, and the opening in which said semiconductorconnection layer is exposed in a part of said organic interlayerinsulating film.
 10. The liquid crystal display device according toclaim 8, wherein said first substrate comprises the gate wiringconnected to a gate electrode of said thin film transistor, a commonelectrode made of a same material as said gate wiring, a gate insulatingfilm formed on said gate wiring and said common electrode, saidsemiconductor layer formed on said gate insulating film, a drain wiringand a source wiring which are connected to a drain electrode and asource electrode of said thin film transistor, respectively, saidorganic interlayer insulating film formed on said drain wiring and saidsource wiring, a first contact hole formed on said common electrode byremoving a part of said gate insulating film and said organic interlayerinsulating film, and a second contact hole formed on said drain wiringor said source wiring by removing a part of said organic interlayerinsulating film.
 11. The liquid crystal display device according toclaim 8, wherein said first substrate comprises the gate wiringconnected to a gate electrode of said thin film transistor, a commonelectrode made of a same material as said gate wiring, a gate insulatingfilm formed on said gate wiring and said common electrode, saidsemiconductor layer formed on said gate insulating film, a drain wiringand a source wiring which are connected to a drain electrode and asource electrode of said thin film transistor, respectively, aprotective insulating film formed on said drain wiring and said sourcewiring, said organic interlayer insulating film formed on saidprotective insulating film, a first contact hole formed on said commonelectrode by removing a part of said gate insulating film, saidprotective insulating film, and said organic interlayer insulating film,and a second contact hole formed on said drain wiring or said sourcewiring by removing a part of said protective insulating film and saidorganic interlayer insulating film.
 12. The liquid crystal displaydevice according to claim 9, wherein said semiconductor connection layeris exposed in whole region of said opening and an area of said openingis smaller than that of said semiconductor connection layer.
 13. Theliquid crystal display device according to claim 8, wherein the sealantis formed from epoxy resin.
 14. The liquid crystal display deviceaccording to claim 8, wherein semiconductor connection layer is formedfrom amorphous silicon.
 15. The liquid crystal display device accordingto claim 8, wherein the seal portion is located near a periphery of thefirst substrate.
 16. The liquid crystal display device according toclaim 8, wherein the sealant is formed from epoxy resin, and thesemiconductor connection layer is formed from an amorphous silicon filmin a region adhering to the sealant so that adhesive force between thesealant and the first substrate is strengthened.
 17. The liquid crystaldisplay device according to claim 8, wherein the same material isamorphous silicon.
 18. The liquid crystal display device according toclaim 8, wherein semiconductor connection layer is formed from amorphoussilicon film forming a channel region of the thin film transistor.
 19. Aliquid crystal display device, comprising: a first substrate providedwith a pixel part where thin film transistors are formed and a sealportion arranged around said pixel part; a second substrate opposed tosaid first substrate; a liquid crystal layer filled between said firstsubstrate and said second substrate; and a sealant provided for saidseal portion in which said first substrate is adhered to said secondsubstrate, wherein said first substrate comprises at least an organicinterlayer insulating film and a terminal portion arranged outside ofsaid seal portion, said seal portion comprises a gate wiring connectedto a gate electrode of said thin film transistors and a gate insulatingfilm formed on said gate wiring, and said gate insulating film in saidseal portion is arranged in contact with said sealant, wherein saidsealant is placed on a semiconductor connection layer made of a samematerial as a semiconductor layer composing said thin film transistorsbetween said terminal portion and a Gate wiring/Drain wiring conversionportion and is surrounded by a protective film, an organic interlayerinsulating film and a transparent conductive film, said semiconductorconnection layer lying between said gate insulating film and saidprotective film partially extends underneath said protective film andthere exists a part where said protective film and said gate insulatingfilm directly contact with each other in said seal portion, and saidsealant is placed on a surface revealing said gate insulating film insaid seal portion.